Steam treatment of soil

ABSTRACT

A soil treatment system, including heat treatment apparatus configured to travel in a forward direction along a plot of ground having a soil surface and configured for disturbing the soil surface and treating associated soil with steam as the heat treatment apparatus travels to provide steam treated soil, and a source of steam in flow communication with the heat treatment apparatus for supplying steam to the heat treatment apparatus. The heat treatment apparatus includes a first heat treatment section having a plurality of rotating blades configured to contact the soil surface and lift and circulate the soil and return the soil to the ground, and a plurality of first steam outlets proximate the rotating blades configured to expose the soil lifted and circulated by the rotating blades to steam from the first steam outlets. The heat treatment apparatus also includes a second heat treatment section having a conveyor configured to receive soil and to return the soil to the ground, a plurality of second steam outlets proximate the conveyor and a blade configured to contact the soil surface and lift the soil onto the conveyor for exposure of the soil on the conveyor to steam from the second steam outlets.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of co-pending U.S. patent application Ser. No. 15/670,303 filed Aug. 7, 2017, entitled STEAM TREATMENT OF SOIL, incorporated herein by reference in its entirety.

FIELD

This disclosure relates to the treatment of soil using steam. More particularly, this disclosure relates to mobile apparatus for treatment of soil onsite using steam.

BACKGROUND

Improvement is desired in the treatment of soil using steam. Treatment of soil with steam is a technique intended to sterilize the soil. It has been observed that steam will kill pests of plant cultures such as weeds, bacteria, fungi and viruses. Steam can also be used to treat soil fatigue. Conventional treatment methods and apparatus either do not effectively treat the soil or cannot do so in a cost-effective manner.

In treating soil with steam, it is desired to effectively treat the soil to achieve benefits, such as killing soil-borne diseases and pathogens, the thermal destruction of seeds in the top layer of the treated soil, such as the seeds of weeds, and treating soil fatigue. In many cases, even if the soil is initially heated by the steam to an effective level, heat escapes rapidly from the top layer and a myriad of new growth from seeds of weeds and the like in the soil appears.

What is desired is apparatus that may be utilized to treat soil with steam onsite and in a manner that effectively not only treats the soil to kill pathogens and treat soil fatigue, but also effectively destroys the viability of weed seeds and the like in the top layer of the treated soil.

SUMMARY

The above and other needs are met by soil treatment systems.

In one aspect, a soil treatment system includes heat treatment apparatus configured to travel in a forward direction along a plot of ground having a soil surface and configured for disturbing the soil surface and treating associated soil with steam as the heat treatment apparatus travels to provide steam treated soil, and a source of steam in flow communication with the heat treatment apparatus for supplying steam to the heat treatment apparatus.

The heat treatment apparatus includes a first heat treatment section having a plurality of rotating blades configured to contact the soil surface and lift and circulate the soil and return the soil to the ground, and a plurality of first steam outlets proximate the rotating blades configured to expose the soil lifted and circulated by the rotating blades to steam from the first steam outlets.

The heat treatment apparatus also includes a second heat treatment section having a conveyor configured to receive soil and to return the soil to the ground, a plurality of second steam outlets proximate the conveyor and a blade configured to contact the soil surface and lift the soil onto the conveyor for exposure of the soil on the conveyor to steam from the second steam outlets.

In another aspect, a soil treatment system includes heat treatment apparatus configured to travel in a forward direction along a plot of ground having a soil surface and configured for disturbing the soil surface and treating associated soil with steam as the heat treatment apparatus travels to provide steam treated soil, and a source of steam in flow communication with the heat treatment apparatus for supplying steam to the heat treatment apparatus.

The heat treatment apparatus includes a blade configured to contact the soil surface and lift and circulate the soil and return the soil to the ground to provide treated soil; a front steam manifold located in front of the blade at a vertical location just slightly above the soil surface, the front steam manifold including a front steam outlet; a mid steam manifold located above a mid-portion of the blade, the mid steam manifold including a mid steam outlet; a rear steam manifold located rearward of the blade, the rear steam manifold including a rear steam outlet; a heat shield located to substantially envelop the blade, the front steam outlet, the mid steam outlet, and the rear steam outlet; and a continuous loop of insulative sheet material trained around rollers and located to travel a lower surface of the loop of insulative sheet material along the treated soil.

In another aspect, a soil treatment system includes heat treatment apparatus configured to travel in a forward direction along a plot of ground having a soil surface and configured for disturbing the soil surface and treating associated soil with steam as the heat treatment apparatus travels to provide steam treated soil, and a source of steam in flow communication with the heat treatment apparatus for supplying steam to the heat treatment apparatus.

The heat treatment apparatus includes a first blade configured to contact the soil surface and lift and circulate the soil and return the soil to the ground; a plurality of steam outlets configured to introduce steam to the soil as it is lifted and circulated; a conveyor configured to receive soil and to return the soil to the ground; a plurality of second steam outlets proximate the conveyor; a second blade configured to contact the soil surface and lift the soil onto the conveyor for exposure of the soil on the conveyor to steam from the second steam outlets. The system also includes a continuous loop of insulative sheet material trained around rollers and located to travel a lower surface of the loop of insulative sheet material along the soil.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages of the disclosure are apparent by reference to the detailed description when considered in conjunction with the figures, which are not to scale so as to more clearly show the details, wherein like reference numbers indicate like elements throughout the several views, and wherein:

FIG. 1 shows apparatus for treatment of soil using steam according to the disclosure.

FIG. 2 is an enlarged view of portions of the apparatus of FIG. 1.

FIG. 3 shows additional components for use with a system for treatment of soil using steam according to the disclosure.

FIG. 4 shows steam supply manifolds arranged in according to the disclosure.

FIG. 5 shows an alternate embodiment of apparatus for treatment of soil using steam according to the disclosure.

FIG. 6 is an enlarged view of a second stage steam treatment section of the apparatus of FIG. 5.

FIG. 7 is an enlarged view of a portion of the apparatus of FIG. 5 configured for covering treated soil with a sheet material.

FIG. 8 shows a further embodiment of apparatus for treatment of soil using steam according to the disclosure.

DETAILED DESCRIPTION

The disclosure relates to mobile apparatus for in-situ treatment of soil using steam.

FIGS. 1-4

With initial reference to FIGS. 1-4, there is shown a steam treatment system 10 having soil treatment apparatus 12 mounted to or pulled by a tractor 14 or other suitable all-terrain vehicle that travels along soil S to be treated. Steam supply lines 16 supply steam from a source of steam 18 to the soil treatment apparatus 12. The source of steam 18 may connect to the soil treatment apparatus 12 as by a hitch 20 or the like connector.

As depicted, the steam treatment system 10 is configured for agricultural settings, with acres of soil to treat. For example, in such a setting, a plot of ground when planted will have a plurality of generally parallel rows of crops. To treat the soil prior to planting crops, the apparatus is configured to treat portions of the soil in row sized increments. It will be appreciated that the system 10 may be otherwise sized for different treatment settings, including smaller and larger settings.

The soil treatment apparatus 12 includes a frame 22 onto which is mounted the components of the apparatus 12. The components include rotatable tiller blades 30, heat shield 32, soil knives 34, front steam supply manifolds 36, mid steam supply manifolds 38, and rear steam supply manifolds 40. In addition, the soil treatment apparatus 12 may include a roll 42 of flexible soil sheet material 42 a, and a soil packer 44. In addition, the apparatus 12 includes fixed soil or clod tines 46 behind the tiller blades 30.

The rotatable tiller blades 30 are conventional roto-tiller blades coupled in a conventional manner to a PTO or power-take-off 14 a of the tractor 14, or otherwise powered for rotation. As shown, the blades 30 are mounted on a rotating shaft 30 a. The blades 30 preferably rotate counter-clockwise as shown by the arrows in FIG. 2, so as to provide a reverse rotation to disturb the soil S and cause disturbed soil, which is elevated and tossed over the blades 30 toward the rear of the apparatus 12 as depicted in FIG. 2.

As shown, the disturbed soil and steam from the manifolds 36-40 mix thoroughly, resulting in a mixture of disturbed soil and steam represented generally by reference character DS in FIG. 2. Treated soil is depicted by reference character TS. The clod tines 46 are fixed fork-like structures upon which the disturbed soil impinges to break the soil into smaller portions. For example, the tines 46 may be provided as by a plate 46 a having descending spikes 46 b. The tines 46 also serve to direct larger portions and organic tillage matter, such as plant stalks and the like, downward and back into the soil as is desired in the tilling of soil.

The heat shield 32 may be of metal plate construction and located and configured around the tiller blades 30 to provide a housing or shroud for containing heat and the disturbed soil during treatment of the soil S using the soil treatment apparatus 10. The heat shield 32 includes an extension 32 a configured to drag along the soil S at the rear behind the rear steam supply manifold 40 and settle the treated soil and retain heat in the upper portion of the treated soil, as explained more fully below. A trailing portion of the shield 32 from which the extension 32 a extends is preferably connected as by a hinge 32 b so that the trailing portion can pivot and maintain the extension 32 a along the surface of the soil S. The connection provided by the hinge 32 b also serves to reduce wear and tear on the heat shield 32.

The soil knives 34 are conventional agricultural soil knives of the type used to drag through soil to break up the soil. The soil knives 34 are desirably located in front of the tiller blades 30 to loosen the soil S to facilitate disturbance of the soil S in a desired manner by the tiller blades 30 to provide the disturbed soil. The soil knives 34 are desirably located within a front portion of the enclosed area of the heat shield 32.

The steam supply manifolds 36, 38 and 40 are in flow communication with the steam supply lines 16 and located within the shroud provided by the heat shield 32. As seen in FIG. 4, each of the manifolds 36-38 are elongate and extend horizontally perpendicular to the direction of travel so as to be aligned with the width of the tiller blades 30. To facilitate application of steam pressure sufficient to avoid plugging of the manifolds from soil, debris and the like, a pair of each of the manifolds 36-40 is provided to span the width of the soil treatment apparatus 12, with each of the manifolds 36-40 connected to one of the steam supply lines 16. In a preferred embodiment, for agriculture settings, dry steam is supplied to the manifolds 36-40 at a temperature of from about 360 to about 425 degrees F., and at a pressure of from about 100 to about 150 psi.

With reference to FIG. 2, each front steam manifold 36 is located at the front of the tiller blades 30, and behind the knives 34, at a vertical location just slightly above the Soil S. The front steam manifold 36 includes steam outlet tubes 36 a, 36 b, and 36 c.

The outlet tubes 36 a are vertically directed and located directly behind the soil knives 34 and have a length configured to terminate proximate a lower end of the knife 34, which is below the soil level S. The outlet tubes 36 b are horizontally directed and have a length configured to terminate about one inch from the ends of the tiller blades 30. The outlet tubes 36 c are parallel to the outlet tubes 36 b, but shorter, and terminate about 6 inches from the tiller blades 30. With reference to FIG. 4, the tubes 36 a, 36 b, and 36 c, are spaced apart on about 12-inch centers and the tubes 36 a, 36 b, and 36 c are staggered relative to one another so that, the tubes 36 a are about 4 inches horizontally spaced from the adjacent tubes 36 b and the tubes 36 c are about 8 inches horizontally spaced from the adjacent tubes 36 a, and about 4 inches horizontally spaced from the adjacent tubes 36 b.

Returning to FIG. 2, the mid steam supply manifold 38 is located above a mid-portion of the tiller blades 30, proximate the center of shaft 30 a onto which the blades 30 are mounted. The mid steam supply manifold 38 includes steam outlet tubes 38 a and 38 b, both of which extend through an upper portion of the shield 32. The tubes 38 a are horizontally directed and have a length configured to terminate about one inch from the ends of the tiller blades 30. The outlet tubes 38 b are parallel to the outlet tubes 36 a, but shorter, and terminate about 6 inches from the tiller blades 30. With reference to FIG. 4, the tubes 38 a and 38 b as sets, with each set spaced apart on about 12-inch centers. The tubes 38 a and 38 b are parallel and aligned, spaced apart by about 2 inches from one another in each set.

With further reference to FIG. 2, the rear steam supply manifold 40 is located rearward of the tiller blades 30 and includes steam outlet tubes 40 a and 40 b, which extend through the shield 32 to dispose the ends of the tubes 40 a just inside the rear of the shield 32 near the soil level, and the tubes 40 b proximate the clod times 46. With reference to FIG. 4, the tubes 40 a and 40 b, are spaced apart on about 12-inch centers.

As will be appreciated, the configuration and location of the manifolds 36-40 and their associated outlet tubes relative to the tiller blades 30 enables treatment of soil using steam and enables steam to be applied close to small soil particles. The apparatus also enables soils to be in suspense with steam for sufficient time with the steam for sterilization of the soil by the steam.

As will also be seen, such as in FIG. 2, the heat shield 32 substantially envelops the tiller blades 30, the front steam outlets 36 a-36 c, the mid steam supply outlets 38 a and 38 b, and the rear steam supply outlets 40 a-40 b so as to reduce the escape of heat during treatment of the soil with the steam from the steam supply outlets. In addition, as explained more fully below, the shield extension 32 a and the sheet material 42 a further serve to forestall the escape of heat from soil during treatment, which enhances the heat treatment of the soil.

The sheet material 42 a is desirably a flexible sheet thermal insulation material having sufficient durability to withstand the rigors of the agricultural setting. For the purpose of example, the sheet material 42 b may be a rubber sheet material having a thickness of about ¼ inch, with a width of from about 6 feet to about 12 feet, and a length of from about 50 to about 100 yards.

The sheet material 42 a is dispensed from the roll 42 by rotation generated by a drive motor 42 b associated with the roll 42. The roll 42 desirably provides the sheet material 42 a in a width and length sufficient to overlie the whole of a row of soil treated. The drive motor 42 b may be electronically linked to the speed of the tractor 14 to facilitate desired deployment of the sheet material 42 a to overlie the treated soil. Desirably, after a pass of the treatment system 10 has been made along a length of soil to be treated, such as the length of a row in an agricultural field, it is desirable to let the sheet material 42 a lie over the treated soil for a time sufficient to effectively sterilize the treated soil, including the killing of weed seeds and the like in the top layer of the treated soil. In this regard, a significant aspect of the disclosure relates to the combination of the outlet tubes 40 a in combination with the shield extension 32 a and the sheet material 42 a.

For example, as the treated soil returns to rest after the tiller blades 30 have passed, the shield extension 32 a serves to smooth the treated soil and to retain heat from escaping from the treated soil. The soil packer 44 also assists to pack and level the soil prior to installation of the sheet material 42 a. In this regard, it has been observed that packing the soil also helps to retain heat in the soil. The sheet material 42 a is deposited over the treated soil as a layer of insulation to retain heat in the treated soil, and especially the upper layer of the treated soil. It has been discovered that the retention of heat provided by this manner of treatment serves to enhance the treatment of the soil to not only treat the soil to kill pathogens, but to also effectively destroy the viability of weed seeds and the like in the top layer of the treated soil.

For the purpose of example, once the tractor 14 has reached the end of a row of soil to be treated, it is preferred to let the sheet material 42 a lie for a time of at least about 3 minutes or more to effectively treat the soil. Then, after sufficient passage of time for treatment, the distal end of the sheet material 42 is retrieved and positioned on a tube 42 c associated with the roll 42 and the drive motor 42 b is reversed to retrieve the sheet material 42 a to again provide the roll 42 of the sheet material 42 a so that the next row of soil may be treated. Retrieval of the sheet material 42 is depicted by reference numeral 42 a′. The system 10 is then ready to treat another row of soil.

The source of steam 18 may include a steam boiler 50, water tank 52, an electrical power generator 54, and fuel 56 for the generator 54, all located on a trailer 58 connected to the soil treatment apparatus 12 by the hitch 20.

FIGS. 5-7

With reference now to FIGS. 5-7, there is shown an alternate embodiment of a steam treatment system 60. The treatment system 60 is similar to the treatment system 10, except it includes a second stage steam treatment section 100 and a sheet material system 110 that does not require retrieval of the of the sheet material.

The system 60 has soil treatment apparatus 62 that is similar to the soil treatment apparatus 12. The apparatus 62 may be mounted to or pulled by a tractor 64 or other suitable all-terrain vehicle that travels along soil S to be treated. Steam supply lines 66 supply steam from a source of steam 68 to the soil treatment apparatus 62. The source of steam 68 may connect to the soil treatment apparatus 62 as by a hitch 70 or the like connector.

The soil treatment apparatus 62 includes a frame 72 onto which is mounted the components of the apparatus 62. The components include rotatable tiller blades 80, heat shield 82, soil knives 84, front steam supply manifolds 86, mid steam supply manifolds 88, and rear steam supply manifolds 90. A soil packer 94 is located to trail the second stage steam treatment section 100. Fixed soil or clod tines 96 are located behind the tiller blades 80. The foregoing described features are similar to the corresponding features described in connection with the apparatus 10.

The rotatable tiller blades 80 are conventional roto-tiller blades coupled in a conventional manner to a PTO or power-take-off 64 a of the tractor 64, or otherwise powered for rotation. The blades 60 are mounted on a rotating shaft 60 a and preferably rotate counter-clockwise to provide a reverse rotation to disturb the soil S and cause disturbed soil, which is elevated and tossed over the blades 60 toward the rear of the apparatus 62. The disturbed soil and steam from the manifolds 86-90 mix thoroughly, resulting in a mixture of disturbed soil and steam DS. Treated soil is depicted by reference character TS.

The heat shield 82 is similar to the heat shield 32 and configured around the tiller blades 60 to provide a housing or shroud for containing heat and the disturbed soil during treatment of the soil S. The heat shield 82 includes an extension 82 a similar to the extension 32 a of the shield and configured to drag along the soil S at the rear behind the rear steam supply manifold 90.

The soil knives 84 are similar to the soil knives 34 and located in front of the tiller blades 30 to loosen the soil S to facilitate disturbance of the soil S in a desired manner by the tiller blades 60 to provide the disturbed soil. The soil knives 64 are desirably located within a front portion of the enclosed area of the heat shield 32.

The steam supply manifolds 86, 88 and 90 are in flow communication with the steam supply lines 66 and located within the shroud provided by the heat shield 82. The manifolds 86-90 are configured in the manner of the manifolds 36-90 described in connection with FIG. 4 and include the outlet tube structures as previously described. For agriculture settings, dry steam is supplied to the manifolds 86-90 at a temperature of from about 360 to about 425 degrees F., and at a pressure of from about 100 to about 150 psi.

Each front steam manifold 86 is located at the front of the tiller blades 60, and behind the knives 64, at a vertical location just slightly above the Soil S. The mid steam supply manifold 68 is located above a mid-portion of the tiller blades 60, proximate the center of shaft 60 a onto which the blades 60 are mounted. The rear steam supply manifold 90 is located rearward of the tiller blades 60. The configuration and location of the manifolds 86-90 and their associated outlet tubes relative to the tiller blades 60 enables treatment of soil using steam and enables steam to be applied close to small soil particles. The apparatus also enables soils to be in suspense with steam for sufficient time with the steam for sterilization of the soil by the steam.

With further reference to FIG. 6, the second stage steam treatment section 100 trails immediately behind the soil treatment apparatus 62. The section 100 is enclosed within a heat shield or shroud 102 for containing heat and the disturbed soil during additional heat treatment of the soil S. The second stage heat treatment section 100 includes a blade 104 located behind the extension 82 a of the apparatus 62, a soil conveyor 106, and steam tubes 108 located to supply steam to the conveyor 106.

The blade 104 is an inclined metal blade configured to engage the treated soil TS behind the apparatus 62 and re-disturb the treated soil TS to provide secondary disturbed soil DS2 and direct the secondary disturbed soil DS2 onto the conveyor 106 for additional steam treatment by steam fed to the conveyor 106 by the steam tubes 108. The conveyor 106 may be provided by a steam permeable conveyor chain located to travel around rollers 106 a.

The rollers 106 a are preferably motor driven to travel the conveyor at a rate to uniformly feed the secondary disturbed soil DS2 on the conveyor 106 at a rate so that the secondary disturbed soil is exposed to steam from the steam tubes for several seconds. In this regard, the steam tubes 108 are in flow communication with the steam supply 66 and are supplied dry steam at a temperature of from about 360 to about 425 degrees F., and at a pressure of from about 100 to about 150 psi. The tubes 108 outlet the steam to and through the conveyor 106 to expose the secondary disturbed soil DS2 to further heating and ejects the soil which is then packed by the packer 64 to provide secondary treated soil TS2.

The sheet material system 110 trails the second stage steam treatment section 100 to cover the secondary treated soil TS2 with a sheet material 112 to insulate the secondary treated soil TS2 and retain heat to enhance the treatment of the soil to not only treat the soil to kill pathogens, but to also effectively destroy the viability of weed seeds and the like. The sheet material 112 may be a rubber sheet material having a thickness of about ¼ inch, with a width of from about 6 feet to about 12 feet

With additional reference to FIG. 7, the sheet material system 110 may be connected to a trailer 114 utilized to carry equipment associated with the source of steam 68. For example, rollers 116 may depend from the trailer 114 for contacting the soil S, with the sheet material 112 trained around the rollers 116 as a continuous loop in the manner of a conveyor belt. A lower surface of the sheet material 112 overlies the secondary treated soil TS2 as the trailer 114 is pulled over the secondary treated soil TS2. The overall length of the sheet material 112 may be from about to about feet, and the lower surface represents about one half of the overall length of the sheet material 112.

The travel rate of the system 100 is such that the lower surface of the sheet material 112 overlies a given section of secondary treated top soil TS2 for a time to enable sufficient heat retention of the treated soil to enhance treatment of the soil to kill pathogens in the soil and to also effectively destroy the viability of weed seeds and the like in the top layer of the treated soil.

As also shown in FIG. 7, the source of steam 68 may include a steam boiler 120, water tank 122, an electrical power generator 124, and diesel fuel 126 for the generator 124, all located on the trailer 114 connected to the soil treatment apparatus 62 by the hitch 70.

FIG. 8

With reference to FIG. 8, there is shown a further embodiment of a steam treatment system 130. The system 130 is substantially similar to the system 60 discussed in connection with FIGS. 5-7, except that it utilizes propane 136 (instead of the diesel fuel 126) as fuel for heating water to provide steam as opposed to diesel fuel.

As will be appreciated, apparatus according to the disclosure enables treatment of soil using steam and enables steam to be applied close to small soil particles. The apparatus also enables soils to be in suspense with steam for sufficient time with the steam for sterilization of the soil by the steam. Further, the system enables sufficient heat retention of the treated soil to enhance treatment of the soil to kill pathogens in the soil and to also effectively destroy the viability of weed seeds and the like in the top layer of the treated soil.

The foregoing description of preferred embodiments for this disclosure has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiments are chosen and described in an effort to provide the best illustrations of the principles of the disclosure and its practical application, and to thereby enable one of ordinary skill in the art to utilize the disclosure in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the disclosure as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled. 

The invention claimed is:
 1. A soil treatment system, comprising: heat treatment apparatus configured to travel in a forward direction along a plot of ground having a soil surface and configured for disturbing the soil surface and treating associated soil with steam as the heat treatment apparatus travels to provide steam treated soil, and a source of steam in flow communication with the heat treatment apparatus for supplying steam to the heat treatment apparatus, the heat treatment apparatus comprising: a first heat treatment section comprising: a plurality of rotating blades configured to contact the soil surface and lift and circulate the soil and return the soil to the ground, and a plurality of first steam outlets proximate the rotating blades configured to expose the soil lifted and circulated by the rotating blades to steam from the first steam outlets; and a second heat treatment section comprising: a conveyor configured to receive soil and to return the soil to the ground, a plurality of second steam outlets proximate the conveyor and a blade configured to contact the soil surface and lift the soil onto the conveyor for exposure of the soil on the conveyor to steam from the second steam outlets.
 2. The soil treatment system of claim 1, wherein the second heat treatment section trails behind the first heat treatment section.
 3. The soil treatment system of claim 1, further comprising a sheet material dispenser configured to cover the treated soil with an insulative sheet material after passage of the first and second heat treatment sections.
 4. The soil treatment system of claim 3, where in the sheet material dispenser comprises a continuous loop of insulative sheet material trained around rollers and located to travel a lower surface of the loop of insulative sheet material along the soil.
 5. The soil treatment system of claim 1, further comprising a first heat shield located to substantially envelop the rotating blades and the first steam outlets.
 6. The soil treatment system of claim 1, further comprising a second heat shield located to substantially envelop the conveyor and the second steam outlets.
 7. The soil treatment system of claim 1, wherein the first heat treatment section includes a plurality of soil knives located forward of the rotating blades and configured to extend below the ground.
 8. The soil treatment system of claim 1, wherein the source of steam comprises a steam boiler, a water tank, and an electrical power generator.
 9. The soil treatment system of claim 8, further comprising a tank of propane located to provide a source of fuel to power the electrical power generator.
 10. A soil treatment system, comprising: heat treatment apparatus configured to travel in a forward direction along a plot of ground having a soil surface and configured for disturbing the soil surface and treating associated soil with steam as the heat treatment apparatus travels to provide steam treated soil, and a source of steam in flow communication with the heat treatment apparatus for supplying steam to the heat treatment apparatus, the heat treatment apparatus comprising: a blade configured to contact the soil surface and lift and circulate the soil and return the soil to the ground to provide treated soil; a front steam manifold located in front of the blade at a vertical location just slightly above the soil surface, the front steam manifold including a front steam outlet; a mid steam manifold located above a mid-portion of the blade, the mid steam manifold including a mid steam outlet; a rear steam manifold located rearward of the blade, the rear steam manifold including a rear steam outlet; a heat shield located to substantially envelop the blade, the front steam outlet, the mid steam outlet, and the rear steam outlet; and a continuous loop of insulative sheet material trained around rollers and located to travel a lower surface of the loop of insulative sheet material along the treated soil.
 11. A soil treatment system, comprising: heat treatment apparatus configured to travel in a forward direction along a plot of ground having a soil surface and configured for disturbing the soil surface and treating associated soil with steam as the heat treatment apparatus travels to provide steam treated soil, and a source of steam in flow communication with the heat treatment apparatus for supplying steam to the heat treatment apparatus, the heat treatment apparatus comprising: a first blade configured to contact the soil surface and lift and circulate the soil and return the soil to the ground; a plurality of steam outlets configured to introduce steam to the soil as it is lifted and circulated; a conveyor configured to receive soil and to return the soil to the ground; a plurality of second steam outlets proximate the conveyor; a second blade configured to contact the soil surface and lift the soil onto the conveyor for exposure of the soil on the conveyor to steam from the second steam outlets; and a continuous loop of insulative sheet material trained around rollers and located to travel a lower surface of the loop of insulative sheet material along the soil. 